1. Field of the Invention
This invention relates to an oil seal assembly suitable for sealing a reciprocating shaft.
2. Description of the Prior Art
As seen in compressors or Stirling engines, the hermetic seal about a rod connecting a driving source with a piston which forms a compression chamber is vital in terms of raising the compression ratio and minimizing leakage of the working gas.
The conventional oil seal assembly includes an annular oil seal the inner peripheral portion of which has a radially inwardly projecting lip of a generally triangular cross section. The lip is kept in pressured contact with a reciprocating shaft by an annular spring disposed at its back. High-pressure gas from a compression chamber is prevented from leaking by the lip and an oil confined within the oil seal. A cutting operation is used to form the lip and to provide the oil seal with a predetermined inner diameter. However, the cutting operation provides neither a stable position for the lip nor a stable inner diameter. There is also an offset between the line along which the urging force of the spring acts and the tip of the lip, thus detracting from oil sealing performance.